org.apache.lucene.search.similarities
Class LambdaDF

java.lang.Object
  org.apache.lucene.search.similarities.Lambda
      org.apache.lucene.search.similarities.LambdaDF

public class LambdaDF
extends Lambda

Computes lambda as docFreq+1 / numberOfDocuments+1.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

LambdaDF()
Sole constructor: parameter-free

Method Summary

Explanation	explain(BasicStats stats) Explains the lambda parameter.
float	lambda(BasicStats stats) Computes the lambda parameter.
String	toString() Subclasses must override this method to return the code of the lambda formula.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

LambdaDF

public LambdaDF()

Sole constructor: parameter-free

Method Detail

lambda

public final float lambda(BasicStats stats)

Description copied from class: Lambda

Computes the lambda parameter.

Specified by:

lambda in class Lambda

explain

public final Explanation explain(BasicStats stats)

Description copied from class: Lambda

Explains the lambda parameter.

Specified by:

explain in class Lambda

toString

public String toString()

Description copied from class: Lambda

Subclasses must override this method to return the code of the lambda formula. Since the original paper is not very clear on this matter, and also uses the DFR naming scheme incorrectly, the codes here were chosen arbitrarily.

Specified by:

toString in class Lambda